1983 Dodge Ram 150 overheated on me. I changed out the thermostat thinking that it must have gotten stuck. It has a new water pump. Alternator belt got tore up when it jumped during overheating. I don't know how to place belt on fan and alternator pulleys. I manuevered belt under fan blades and it there is no space to go into fan belt pulley.

I would welcome any diagram or advice on installing belt.

I don't have the routing diagram, but your belt likely goes around the bottom of the crankshaft pulley, around the alternator, then around the water pump/fan pulley then back to the crankshaft.

Make sure when you put it on that it's lined up, you have the older V-belts, so there will be multiple grooves on some of the pulleys.

As far as your overheating problem, I'd suspect the radiator. You can have it tested for flow at a radiator shop. Just a 10-20% flow restriction in your radiator can make a huge difference in cooling.